Disulfide-Directed Multicyclic Peptides for Chimeric Antigen Receptors Targeting Solid Tumors
Xiaoting Meng1,2, Keke Fu1, Yawei Liu1
1Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China.
Abstract:
The clinical application of chimeric antigen receptor (CAR) T cell therapy in solid tumors remains limited due to significant safety concerns, particularly "on-target, off-tumor" toxicity and cytokine release syndrome (CRS). Here, we describe a class of CARs that employ disulfide-directed multicyclic peptides (DDMPs) as compact antigen-recognition domains targeting the tumor-associated antigens HER2 and TROP2. DDMP-based CAR T cells exhibited antigen density-dependent cytotoxicity in vitro and in vivo, efficiently eliminating cells with high antigen expression while sparing cells with low antigen levels, thereby mitigating on-target, off-tumor toxicity. In addition, DDMP-based CAR T cells secreted markedly lower levels of pro-inflammatory cytokines upon targeted killing, reducing CRS risk. Mechanistic analyses revealed that this favorable combination of restrained cytokine release and density-gated killing is associated with distinct T cell signaling pathway engagement and reduced cell avidity relative to conventional single-chain variable fragment (scFv)-based CAR T cells. Collectively, these findings establish DDMP-based CARs as a promising framework for engineering safer, yet efficacious, CAR T therapies for solid tumors.
Insights
New chimeric antigen receptor (CAR) T cells using disulfide-directed multicyclic peptides (DDMPs) show improved safety for solid tumors. These DDMP-CAR T cells target tumors based on antigen density, reducing toxicity and cytokine release syndrome (CRS).
Area of Science:
- Immunotherapy
- Oncology
- Molecular Biology
Background:
- Chimeric antigen receptor (CAR) T cell therapy faces challenges in solid tumors, including "on-target, off-tumor" toxicity and cytokine release syndrome (CRS).
- Current CAR T cell designs often lack specificity, leading to adverse effects.
- Novel antigen-recognition domains are needed to improve CAR T cell safety and efficacy.
Purpose of the Study:
- To develop a new class of CARs utilizing disulfide-directed multicyclic peptides (DDMPs) as antigen-recognition domains.
- To evaluate the safety and efficacy of DDMP-based CAR T cells in targeting solid tumors expressing HER2 and TROP2.
- To investigate the mechanisms underlying the improved safety profile of DDMP-CAR T cells.
Main Methods:
- Engineered CAR T cells employing DDMPs targeting tumor-associated antigens HER2 and TROP2.
- In vitro and in vivo assays to assess antigen density-dependent cytotoxicity.
- Measurement of cytokine secretion and T cell signaling pathway engagement.
- Comparison with conventional single-chain variable fragment (scFv)-based CAR T cells.
Main Results:
- DDMP-CAR T cells demonstrated antigen density-dependent cytotoxicity, effectively eliminating high-expressing tumor cells while sparing low-expressing cells.
- Reduced secretion of pro-inflammatory cytokines was observed, indicating a lower risk of CRS.
- DDMP-CAR T cells showed distinct T cell signaling and reduced cell avidity compared to scFv-CAR T cells.
- Mitigation of "on-target, off-tumor" toxicity was achieved.
Conclusions:
- DDMP-based CARs represent a promising strategy for developing safer and more effective CAR T cell therapies for solid tumors.
- The antigen density-gated killing and restrained cytokine release offer a significant safety advantage.
- This novel CAR framework has the potential to overcome current limitations in solid tumor immunotherapy.
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